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/Users/fmalpartida/development/ardWorkspace/LiquidCrystal_I2C/LiquiCrystal_I2C/LiquidCrystal_SR_LCD3.cpp
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    00001 // ---------------------------------------------------------------------------
    00002 // Originally Created by Francisco Malpartida on 2011/08/20.
    00003 // Copyright 2011 - Under creative commons license 3.0:
    00004 //        Attribution-ShareAlike CC BY-SA
    00005 //
    00006 // This software is furnished "as is", without technical support, and with no
    00007 // warranty, express or implied, as to its usefulness for any purpose.
    00008 //
    00009 // 2012/01/21 - Marc MERLIN
    00010 // This library, LiquidCrystal_SR_LCD3, was forked off LiquidCrystal_SR which
    00011 // used a different wiring than the Pebble and Pebblev2 (just released by
    00012 // freetronics in the arduino miniconf as part of linux.conf.au 2012) and
    00013 // therefore this code organizes the output data differently.
    00014 //
    00015 // Upstream source for this module is
    00016 // https://github.com/marcmerlin/NewLiquidCrystal
    00017 //
    00018 // Thread Safe: No
    00019 // Extendable: Yes
    00020 //
    00021 // @file LiquidCrystal_SR_LCD3.h
    00022 //
    00023 //  Connects an LCD using 3 pins from the Arduino, via an 8-bit
    00024 //  ShiftRegister (SR from now on).
    00025 //  The original port source for this module is https://github.com/marcmerlin/NewLiquidCrystal
    00026 //  The 'FastIO' merge has madethis code 4 times faster.
    00027 //
    00028 // @brief
    00029 // This is a port of the ShiftRegLCD library from raron and ported to the
    00030 // LCD library.
    00031 //
    00032 // The functionality provided by this class and its base class is identical
    00033 // to the original functionality of the Arduino LiquidCrystal library and can
    00034 // be used as such.
    00035 //
    00036 // Pinout for this code is used by derivatives of the original LCD3Wire page:
    00037 // http://www.arduino.cc/playground/Code/LCD3wires
    00038 //
    00039 // This includes the LCA (linux.conf.au) Arduino Miniconf Pebble:
    00040 // http://shieldlist.org/luke-weston/pebble
    00041 // https://github.com/lukeweston/Pebble
    00042 //
    00043 // It also includes the Pebble v2:
    00044 // http://www.arduinominiconf.org/index.php/Pebble_V2.0_Instructions
    00045 // http://www.freetronics.com/pages/pebble-v2
    00046 // https://github.com/lukeweston/pebble20/blob/master/README.md
    00047 // https://github.com/lukeweston/pebble20/blob/master/pebble-sch.pdf
    00048 //
    00049 // Shiftregister connection description:
    00050 // MC14094 input:  Arduino digital pin 2=Clock, pin 3=Data, pin 4=Strobe
    00051 // MC14094 output: Q8=DB4, Q7=DB5, Q6=DB6, Q5=DB7, Q4=E, Q3=RW, Q2=RS, Q1=None
    00052 //
    00053 //   +--------------------------------------------+
    00054 //   |    Arduino (ATMega 168 or 328)             |
    00055 //   |    D02           D03           D04         |
    00056 //   +----+-------------+-------------+-----------+
    00057 //        |4            |5            |6
    00058 //        |1            |2            |3
    00059 //   +----+-------------+-------------+-----------+
    00060 //   |    Strobe        Data          Clock       |
    00061 //   |    MC14094 8-bit shift/latch register      |
    00062 //   |    Q8   Q7   Q6   Q5   Q4   Q3   Q2   Q1   |
    00063 //   +----+----+----+----+----+----+----+----+----+
    00064 //        |11  |12  |13  |14  |7   |6   |5   |4
    00065 //        |11  |12  |13  |14  |6   |5   |4
    00066 //   +----+----+----+----+----+----+----+---------+
    00067 //   |    DB4  DB5  DB6  DB7  E    RW   RS        |
    00068 //   |               LCD KS0066                   |
    00069 //   +--------------------------------------------+
    00070 //
    00071 // 3 Pins required from the Arduino for Data, Clock, and Enable/Strobe.
    00072 //
    00073 // This code was inspired from LiquidCrystal_SR from
    00074 // http://code.google.com/p/arduinoshiftreglcd/
    00075 // but was written for implementing LiquidCrystal support for the Pebble
    00076 // and Pebblev2 (see below).
    00077 // The Pebbles's LCD and shift register wiring were inspired from this
    00078 // original page:
    00079 // http://www.arduino.cc/playground/Code/LCD3wires
    00080 //
    00081 // Pebbles and the LCD3Wires design are compatible hardware-wise, but
    00082 // the LCD3Wire code does not work with arduino 1.0 anymore and is generally
    00083 // quite limited in functionality compared to this framework that provides the
    00084 // entire LiquidDisplay functionality.
    00085 // Why not just use the LiquidCrystal_SR pinout?
    00086 // - LCD3Wire was first and therefore have hardware that was designed with
    00087 //   incompatible (IMO better if you don't mind 3 wires) pinout.
    00088 // - The pinout used here is same saner (the 4 bits for the LCD are all in one
    00089 //   nibble of the shift register, not spread across 2 like in the
    00090 //   LiquidCrystal_SR pinout)
    00091 //
    00092 // Note however that LiquidCrystal_SR while a bit more complex wiring and code
    00093 // wise, supports non latching shift registers and it a few percent faster than
    00094 // this code since it can address the LCD enable pin without having to send
    00095 // a pulse through the shift register like the LCD3Wires setup requires.
    00096 //
    00097 // This code makes sure to properly follow the specifications when talking
    00098 // to the LCD while using minimal delays (it's faster than the LCD3wire and aiko
    00099 // pebble code).
    00100 //
    00101 // @author Marc MERLIN - marc_soft<at>merlins.org.
    00102 // ---------------------------------------------------------------------------
    00103 #include <stdio.h>
    00104 #include <string.h>
    00105 #include <inttypes.h>
    00106
    00107 #if (ARDUINO <  100)
    00108 #include <WProgram.h>
    00109 #else
    00110 #include <Arduino.h>
    00111 #endif
    00112 #include "FastIO.h"
    00113 #include "LiquidCrystal_SR_LCD3.h"
    00114
    00115
    00116 // STATIC helper functions
    00117 // ---------------------------------------------------------------------------
    00118
    00119
    00120 // CONSTRUCTORS
    00121 // ---------------------------------------------------------------------------
    00122 // Assuming 1 line 8 pixel high font
    00123 LiquidCrystal_SR_LCD3::LiquidCrystal_SR_LCD3 ( uint8_t srdata, uint8_t srclock,
    00124                                               uint8_t strobe )
    00125 {
    00126         init ( srdata, srclock, strobe, 1, 0 );
    00127 }
    00128
    00129
    00130 // PRIVATE METHODS
    00131 // ---------------------------------------------------------------------------
    00132
    00133 //
    00134 // init
    00135 void LiquidCrystal_SR_LCD3::init( uint8_t srdata, uint8_t srclock, uint8_t strobe,
    00136                                  uint8_t lines, uint8_t font )
    00137 {
    00138         // Initialise private variables
    00139         // translate all pins to bits and registers
    00140         // pinMode to OUTPUT, Output LOW
    00141
    00142    _srdata_bit = fio_pinToBit(srdata);
    00143    _srdata_register = fio_pinToOutputRegister(srdata);
    00144    _srclock_bit = fio_pinToBit(srclock);
    00145    _srclock_register = fio_pinToOutputRegister(srclock);
    00146    _strobe_bit = fio_pinToBit(strobe);
    00147    _strobe_register = fio_pinToOutputRegister(strobe);
    00148
    00149    // Little trick to force a pulse of the LCD enable bit and make sure it is
    00150    // low before we start further writes since this is assumed.
    00151
    00152    write4bits(0);
    00153
    00154    _displayfunction = LCD_4BITMODE | LCD_1LINE | LCD_5x10DOTS;
    00155 }
    00156
    00157 // PUBLIC METHODS
    00158 // ---------------------------------------------------------------------------
    00159
    00160
    00161 /************ low level data pushing commands **********/
    00162
    00163 // Code below was borrowed from LCD3Wire from
    00164 // http://www.arduino.cc/playground/Code/LCD3wires
    00165
    00166 // bitmasks for control bits on shift register
    00167 #define SR_EN_BIT B00010000   // LCD Data enable bit.
    00168 #define SR_RW_BIT B00100000   // RW can be pinned low since we only send
    00169 #define SR_RS_BIT B01000000   // LOW: command. HIGH: character.
    00170
    00171 void LiquidCrystal_SR_LCD3::send(uint8_t value, uint8_t mode)
    00172 {
    00173    uint8_t nibble;
    00174
    00175    mode = mode ? SR_RS_BIT : 0; // RS bit; LOW: command.  HIGH: character.
    00176
    00177    nibble = value >> 4; // Get high nibble.
    00178    write4bits(nibble | mode);
    00179
    00180    //delay(1); // This was in the LCD3 code but does not seem needed -- merlin
    00181
    00182    nibble = value & 15; // Get low nibble
    00183    write4bits(nibble | mode);
    00184 }
    00185
    00186 void LiquidCrystal_SR_LCD3::write4bits(uint8_t nibble)
    00187 {
    00188    nibble &= ~SR_RW_BIT; // set RW LOW (we do this always since we only write).
    00189
    00190    // Send a High transition to display the data that was pushed
    00191    nibble |=  SR_EN_BIT; // LCD Data Enable HIGH
    00192    _pushOut(nibble);
    00193    nibble &= ~SR_EN_BIT; // LCD Data Enable LOW
    00194    _pushOut(nibble);
    00195 }
    00196
    00197 // push byte to shift register and on to LCD
    00198 void LiquidCrystal_SR_LCD3::_pushOut(uint8_t nibble)
    00199 {
    00200    // Make data available for pushing to the LCD.
    00201    fio_shiftOut(_srdata_register, _srdata_bit, _srclock_register, _srclock_bit, nibble, LSBFIRST);
    00202
    00203    // Make new data active.
    00204    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
    00205    {
    00206       fio_digitalWrite_HIGH(_strobe_register, _strobe_bit);
    00207       waitUsec( 1 ); // strobe pulse must be >450ns (old code had 10ms)
    00208       fio_digitalWrite_SWITCHTO(_strobe_register, _strobe_bit,LOW);
    00209    }
    00210    waitUsec( 40 ); // commands need > 37us to settle
    00211 }

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